Fast file server methods and system

ABSTRACT

The invention provides, in one aspect, an improved system for data access comprising a file server that is coupled to a client device or application executing thereon via one or more networks. The server comprises static storage that is organized in one or more directories, each containing, zero, one or more files. The server also comprises a file system operable, in cooperation with a file system on the client device, to provide authorized applications executing on the client device access to those directories and/or files. Fast file server (FFS) software or other functionality executing on or in connection with the server responds to requests received from the client by transferring requested data to the client device over multiple network pathways. That data can comprise, for example, directory trees, files (or portions thereof), and so forth.

PRIORITY CLAIM

This application is a continuation of U.S. application Ser. No.11/845,511 filed 27 Aug. 2007 which issued as U.S. Pat. No. 8,392,529,the teaching of which is explicitly incorporated herein by reference inits entirety.

BACKGROUND OF THE INVENTION

The invention pertains to digital data processing and, moreparticularly, to methods and apparatus for accessing and/or deliveringdata in a client-server environment. The invention has application inimproving file and data access over local area networks, the Internet,and other networks.

Traditional file servers or network attached storage (NAS) devicessupport access requests received from networked client devices (e.g.,PCs, workstations and the like) using network file system capabilitiesbuilt in to the server operating system—which may be, for example, Linuxor Microsoft Windows Server. Typically, these file systems, e.g.SMB/CIFS, allow the clients to access files and directories maintainedon the server as if they were local to the requesting clientsthemselves—albeit, the transfers take place via the network and, as aresult, are traditionally much slower.

Thus, for example, file transfers from a NAS to a client device may beas slow as 10-50 Mbyte/s, even if Gigabit-Ethernet—which has atheoretical peak bandwidth of about 110 Mbyte/s—is used as the network.The discrepancy is more pronounced when actual transfer speeds of 10-50Mbyte/s are measured against the read performance delivered by fast RAIDsystems of the type often attached to high-performance file servers.Those RAID systems are capable of delivering at rates of 200-300MByte/s, or even higher for sufficiently large sequential reads.

Data input/output (I/O) performance is a critical component in dataintensive applications such as, by way of non-limiting example, signalprocessing applications, visualization applications, and the like.

An object of the invention is to provide improved methods and systemsfor digital data processing and, more particularly, by way ofnon-limiting example, for accessing and/or delivering data in aclient-server environment.

A related object of the invention is to provide such methods and systemsas improve the speed of data transfer between file servers and clientdevices.

A still further related object of the invention is to provide suchmethods and systems as reduce the gap between high RAID performance andthe performance usable at the application level, e.g., when a network isdisposed in between.

SUMMARY OF THE INVENTION

The foregoing are among the objects attained by the invention whichprovides, in one aspect, an improved system for data access comprising afile server that is coupled to a client device via one or more networks.The server comprises static storage that is organized in one or moredirectories, each containing, zero, one or more files. The server alsocomprises a file system operable, in cooperation with a file system onthe client device, to provide authorized applications executing on theclient device access to those directories and/or files. Fast file server(FFS) software or other functionality executing on or in connection withthe server responds to requests received from the client device or anapplication executing thereon (collectively, “client”) by transferringrequested data to the client in parallel over multiple network pathways.That data can comprise, for example, directory trees, files (or portionsthereof), and so forth.

Related aspects of the invention provide systems as described above inwhich the server stores a configuration file that is accessible byauthorized clients (e.g., authorized applications executing on theclient device) and that identifies one or more network interfaces overwhich the requested data can be transferred. Further related aspects ofthe invention provide systems as described above in which theconfiguration file additionally contains one or more security keys thatcan be used by the client and the server in connection with a requesteddata transfer.

Yet still further related aspects of the invention provide systems asdescribed above in which the file system of the server controls accessto the configuration file by the client. Such control can be based, forexample, on access permissions associated with the configuration fileand with the executing application.

Still further aspects of the invention provide systems as describedabove in which the client (e.g., an application executing on the clientdevice) requests access to the configuration file and, if successful,generates a request for further data on the server. According to relatedaspects of the invention, the application generates such a request alongwith one or more of the security keys provided in the configurationfile. In further related aspects of the invention, the applicationgenerates such a request on one or more network interfaces identified inthat file. As noted above, the further data that is the subject of sucha request can comprise, for example, directory trees, files (or portionsthereof), and so forth.

Further aspects of the invention provide systems as described above inwhich the FFS functionality executing on (or in connection with) theserver listens for requests on network interfaces identified in theconfiguration file. According to further related aspects of theinvention, it listens only on those network interfaces that areconnected to physically independent networks. Still further relatedaspects of the invention provide systems as described above in which theFFS functionality uses security keys provided with requests to validatethose requests.

According to still further aspects of the invention, the FFSfunctionality responds to requests received from the client device bytransferring requested data with the client via the multiple networkconnections over which those requests were received.

Further aspects of the invention provide systems as described above inwhich the server is coupled to multiple client devices via one or morenetworks. In such systems, the server responds to requests received fromeach client device by transferring requested data to that client deviceover multiple network pathways. According to related aspects of theinvention, the configuration file specifies a different subset ofnetwork interfaces for each client (e.g., each client device and/orapplication executing thereon).

Still other aspects of the invention provide methods for transferringdata between a server and one or more client devices paralleling theforegoing.

These and other aspects of the invention are evident in the drawings andin the description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the invention may be attained byreference to the drawings, in which:

FIG. 1 depicts a digital data processing system according to theinvention;

FIG. 2 is a further depiction of the digital data processing system ofFIG. 1; and

FIG. 3 depicts a method of operation of the system of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

Architecture

FIGS. 1 & 2 depict a digital data processing system 10 according to theinvention. The system includes a file server 12 that is coupled to aclient device 14 and, more typically, multiple client devices 14-18 viaa network 20 and, more typically, multiple networks 20-22.

Server 12 may comprise a conventional file server and/or networkattached storage (NAS) (collectively, “server” or “file server”) of thetype conventionally known in the art, as adapted in accord with theteachings hereof. Although only one server is shown in the drawing, itwill be appreciated that the invention can be practiced with more suchservers.

The server includes static storage that maintains user, application,enterprise or other data organized in the conventional manner known inthe art—here, in one or more directories, each containing, zero, one ormore files. In other embodiments, such data may be organized asserialized objects and/or in other manners known in the art. Storagedevice 24 typically comprises one or more disk drives (as shown) and,preferably, one or more high-speed RAID devices—though, in otherembodiments, tape drives, ROM, RAM, Flash Memory, and/or CD-ROM devicesmay be used instead or in addition. Regardless, such storage device(s)24 are of the type conventionally known in the art as adapted in accordwith the teachings hereof.

The server 12 also comprises a file system 30 that forms part of and/orcooperates with a native operating system 32. Both of these componentsare of the type conventionally known in the art, as adapted in accordwith the teachings hereof. Thus, for example, operating system 32 maycomprise Linux or Microsoft Windows Server, both by way of non-limitingexample and, file system 30 may comprise NTFS, EXT3, or XFS, again, byway of non-limiting example and by be exported by the operating systemusing a protocol such as SMB/CIFS or NFS, again, by way of non-limitingexample. By way of said export protocols the file system 30 operates incooperation with file systems 34-38 (discussed below) on the clientdevices 14-18 to provide authorized applications executing on the clientdevice access to those directories and/or files.

Server 12 further comprises a fast file server (FFS) module 46—here,embodied in software executing on server 12, but in other instantiationsembodied in hardware executing in conjunction with server 12—thatresponds to requests received from a client device 14-18 by transferringrequested data (e.g., directory trees, files (or portions thereof), andso forth) with that client device over multiple networks 20-22.

Server 12 further comprises one or more configuration files 48 thatstore identities of one or more network interfaces over which theclients devices 14-18 may request data transfers. In preferredembodiments, the configuration file(s) 48 additionally store one or moresecurity keys that can be used to validate and/or identify eachrequested data transfer. In the illustrated embodiment, theconfiguration files 38 are maintained in the conventional manner onstorage unit 24, though, in other embodiments they may be storedelsewhere. The file(s) 48 may be text-based (e.g., XML), binary, orotherwise.

In the illustrated embodiment, file system 30 of the server 12 controlsaccess to the configuration file(s) 48 in the conventional manner, e.g.,using permissions (or other access controls) set so that only authorizedusers or applications (hereinafter, collectively, applications)executing on the client devices 14-18 can access the file(s) 48.

Networks 20-22 comprise local area networks (LANs), wide area networks(WANs), metropolitan area networks (MANs), or other networks of the typecommonly known in the art supporting communications between client andserver devices (and including conventional infrastructure, such asswitches 26-28). These may be based in the Internet Protocol (IP) orother protocols, and they may include wireless, wired, satellite and/orother communication mechanisms of the type known in the art. Thenetworks 20-22 may of the same variety (e.g., both megabit Ethernet, byway of non-limiting example) or of mixed varieties (e.g., megabitEthernet and conventional Ethernet, again, by way of non-limitingexample). Though two such networks are shown in the illustration, theinvention contemplates a greater or lesser number thereof.

Client devices 14-18 comprise personal computers, workstations, embeddedprocessors, single-board computers, personal digital assistants or otherdigital data processing device conventional in the art capable ofcooperating in a client-server network and of executing software (here,referred to as “applications” or “software applications”) requiringaccess to storage unit 24. In the illustrated embodiment, those devicesare remotely disposed from the server 12 and coupled for communicationswith it via network media 20-22 operating in accord with the TCP/IPprotocol. In other embodiments, one or more of the client devices 14-18are coupled with the sever 12 via a combination of network media (e.g.,Ethernet and so forth) as well as via direct wired or wireless media(e.g., USB interconnect, firewire interconnect, Bluetooth, infrared, andso forth). Those applications, labeled 50-54, respectively, executing onthe respective client devices may comprise signal processingapplications, visualization applications, and so forth. The clientdevices 14-18 may be of the same and/or mixed varieties. And, thoughshown in the drawing coupled to server 12 via a common set of networks20-22, may be so coupled on sets of disparate (and/or, possiblyoverlapping) networks.

Like server 12, client devices 14-16 comprise respective file systems34-38 that form part of and/or cooperate with respective nativeoperating system 40-44. These, too, are of the type conventionally knownin the art, as adapted in accord with the teachings hereof. Thus, forexample, operating systems 40-44 may comprise Linux or Microsoft WindowsXP, both by way of non-limiting example; and, file systems 34-38 maycomprise SMB/CIFS or NFS clients, again, by way of non-limiting example.

Operation

FIG. 3 depicts operation of the system 10 in connection with a clientrequest for access to storage 24. Although the discussion focuses onrequests by application 50 of device 14, it will be appreciated thatrequests by other applications and/or devices (collectively, “clients”)proceed similarly.

In step 60, client device 14 mounts storage device 24 (or a volumetherein) as a “share” (in Windows terminology) or otherwise. This can beeffected by a user of device 14, application 50 executing thereon and/orby the operating system 40 (e.g., as part of a start-up routine), thoughfor purposes of the discussion that follows, mounting will be assumed tobe effected by the application 50. Mounting proceeds in the conventionalmanner, as mediated by the operating system 40, file system 34 of theclient device, and file system 30 of the server. Per convention, anyand/or all of these may prohibit mounting unless the requesting userand/or application 50 has appropriate security permissions.

Assuming mounting is successful, client application 50 requests accessto configuration file 48 on storage device 24. See step 62. In theillustrated embodiment, this is for READ access to the file 48, though,other embodiments may provide for WRITE, LOCK, or other access to thatfile 48. Regardless, processing of the request for (read) accessproceeds in the conventional manner, as mediated by the operating system40, file system 34 of the client device 14, and file system 30 of theserver. As above and per convention, any and/or all of these mayprohibit access unless the requesting user and/or client application 50has appropriate security permissions.

Assuming access to file 48 is granted, the client application 50 obtainsfrom that file 48 identifications of network interfaces (e.g., ports)and security keys. The client application 50 then generates a requestfor access to data (e.g., a directory tree, file or portion thereof)using those IDs and keys. See step 64. In the discussion that follows,this is assumed to be a request for READ access, although, requests forOPEN, CLOSE, SEEK, WRITE, DELETE FILE, RENAME FILE, MOVE FILE, and soforth, access are similarly handled. The commands are issued in theconventional ordering (e.g., READ, WRITE OR CLOSE following OPEN) andcan specify a previously opened file or a file name.

Although, in some embodiments, the access request of step 62 can be madevia the respective file systems 40, 34, in the illustrated embodiment,that request is made directly by client application 50 to the FFS module46 of the server 12. To this end, the protocol for communicationsbetween the client application 50 and FFS module 46 can be simplerand/or more specialized than traditional file system access requests,thereby facilitating higher performance than standard network filesystems. Moreover, that protocol can be implemented on top of physicalor logical network layers which are not supported in a straight forwardway by standard network file systems. An example is DAPL on Infinibandnetworks.

The request specifies the data structure (e.g., directory tree, file,etc.) to be accessed, as well as the security keys (identified in theconfiguration file 48) for identifying and validating the request. Inthe illustrated embodiment, the request is transferred, in parallel,over each network interface (identified in the configuration file 48)over which the client application 50 specifies access to occur, though,in other embodiments, the request may be transmitted by remote procedurecall (RPC), COM, DCOM, CORBA or otherwise, and may include identifiersfor each such network interface.

In step 66, the FFS module 46—which, in the illustrated embodiment,listens for requests on network interfaces identified in theconfiguration file 48—validates the request received in step 64. Thisincludes verifying that the security keys provided in the request arevalid, that the application 50 has permission (per the file system 34)for access to the requested data (e.g., directory tree and/or file) andthat network interfaces specified for the request are available for thetransfer. In some embodiments, the FFS module 46 listens for and/orvalidates requests only for transfers on physically independentnetworks. In some embodiments, the FFS module 46 can implementvalidation independently of the file system 32. In other embodiments, itutilizes the operating system 32 and file system 30 for at least some ofthese purposes.

Assuming the FFS module 46 validates the request, the module 46 mediatesthe data transfer as between the storage device 24 (via the server'sfile system 32) and the client application 50 (via the specifiedinterfaces to networks 20-22). For example, in the case of a READoperation, the FFS module obtains the requested data (e.g., file blocksor directory tree) and transmits it to the application 50 concurrentlyover the multiple network pathways specified by those interfaces. Seestep 68. Thus, typically, for example, the FFS module transmits therequested data to the client application 50 over two or more separatenetworks 20, 22; however, it may (depending on the specified interfaces)send the data over two separate channels on the same network (e.g., aswhere per-channel bandwidth is rate-limited). In the case of WRITE orother operations, the FFS exchanges the requisite information with theclient application 50 over those interfaces and duly writes it to thestorage device 24.

Once the FFS module 46 has validated access to a given file, directorytree and so forth, the application 50 may continue making requests(e.g., successive read or write requests) without further validation.This is reflected in steps 70-72.

Although the discussion focuses on responses by FFS module 46 torequests from client application 50 executing on device 14, the module46 responds similarly to other applications on that device 14, as wellas to other applications on other devices 16-18. Thus, the FFS module 46of the illustrated embodiment responds to requests received from eachsuch client by transferring requested data to that client over multiplenetwork interfaces—and, therefore, network pathways—specified in therequest. These may be common sets of pathways, partially overlappingsets of pathways, or entirely disparate sets of pathways.

EXAMPLE

An example of an implementation of system 10 for medical visualizationis as follows. In the implementation described here, the client devices14-18 are presumed to be visualization servers, which process largemedical image studies stored on the file server 12. Upon selection of astudy by a user, the data has to be loaded as fast as possible tominimize waiting time.

FFS module 46 is implemented as a process (e.g. a Windows.™. service)running on file server 12, subsequently referred to as “Service.” Uponstartup, the Service writes a file (configuration file 48) into eachdirectory tree to be “exported,” i.e., available for access by a clientdevice 14-18. Those directory trees are exported as standard MicrosoftWindows Shares. The configuration file 48 has read permissions which areas restrictive as the most restrictive read permissions of any of thefiles in that directory tree. The configuration file 48 contains anaccess key randomly generated by the Service, as well as IP addresses ofthe network interfaces of the file server and the TCP/IP port on whichthe Service listens for incoming connections.

Each client device 14-18 which has access to the Windows Share and haspermission to read the configuration file 48 can use the FFS module 46for fast file transfer. It connects to the network interfaces and portspecified in the configuration file 48. It transmits the contents of theaccess key (thereby proving that it had read permission to theconfiguration file 48). On the connection linked to each of the networkinterfaces the same session key is transmitted, thereby associatingthese links with one logical connection.

A data read command is satisfied by the Service using multiplesimultaneous threads and double buffering. One thread reads the datafrom the disk 24 or RAID device. One thread per network interfacetransmits the data. Thereby effectively parallelizing disk read andconcurrent data transmission on all network interfaces.

CONCLUSION

Described above are systems and methods meeting the aforesaid objects,among others. It will be appreciated that the embodiments shown anddescribed herein are merely examples of the invention and that otherembodiments incorporating changes therein fall within the scope of theinvention. Thus, by way of non-limiting example, it will be appreciatedthat the invention can be practiced with peer-to-peer networks, gridnetworks and so forth, wherein the role of “server” is played by a setof one or more devices in such networks and the role of “client” isplayed by a set (possibly overlapping) of one or more (other) devices inthe network.

What is claimed is:
 1. A system for a client to access data comprising:a file server; a plurality of networks; a configuration file stored onthe file server which identifies from the plurality of networks, one ormore network interfaces over which data can be transferred between thefile server and the client; a client device in communication with thefile server via at least one of the plurality of networks, where theclient device is authorized to receive the configuration file; and afast file server executing in connection with the file server thatresponds to requests received from the client device by transferringrequested data to the client device over the one or more networkinterfaces specified by the configuration file.
 2. The system of claim1, where the data comprises any of directory trees, files, or portionsthereof.
 3. The system of claim 1, further comprising one or moresecurity keys that can be used by one or both the client and the serverin connection with a requested data transfer.
 4. The system of claim 3,where the one or more security keys are contained in the configurationfile.
 5. The system of claim 3, where the one or more security keys canbe used to validate a requested data transfer.
 6. The system of claim 3,where the one or more security keys can be used to identify a requesteddata transfer.
 7. The system of claim 1, where the file server controlsaccess to the configuration file.
 8. The system of claim 7, where thefile server controls access by way of access permissions associated withthe configuration file.
 9. The system of claim 1, where the fast fileserver listens for requests on network interfaces identified in theconfiguration file.
 10. The system of claim 1, where the fast fileserver responds to requests received from the client by transferringrequested data to the client device via the one or more networkinterfaces specified by the configuration file.
 11. A system for aclient to access data comprising: a file server; a plurality ofnetworks; a configuration file stored on the file server whichidentifies from the plurality of networks, one or more networkinterfaces over which data can be transferred between the file serverand the client; a plurality of client devices, each coupled forcommunications with the file server via the plurality of networks, whereeach of the plurality of client devices is authorized to receive theconfiguration file; and a fast file server executing in connection withthe file server that responds to requests received from the client bytransferring requested data to one or more of the plurality of clientdevices over the one or more network interfaces specified by theconfiguration file.
 12. The system of claim 11, where the fast fileserver transfers data requested by a first client device of theplurality of client devices to the first client device over a first setof network interfaces and data requested by a second client device ofthe plurality of client devices to the second client device over asecond set of network interfaces.
 13. The system of claim 12, where thefirst set of network interfaces and the second set of network interfaceshave one or more network pathways in common.
 14. The system of claim 12,where the first set of network interfaces and the second set of networkinterfaces have all network interfaces in common.
 15. The system ofclaim 12, where the first set of network interfaces and the second setof network interfaces have no network interfaces in common.
 16. A methodof improved data transfer between a file server and a client comprising:communicating with a file server via at least one of a plurality ofnetworks, where the file server includes a configuration file stored onthe file server which identifies from the plurality of networks, one ormore network interfaces over which data can be transferred between thefile server and the client; verifying the authority of the client toreceive the configuration file; and acting on a request by the client totransfer requested data, where the requested data is transferred overthe one or more network interfaces specified by the configuration file.